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Rollup merge of #97271 - JohnTitor:issue-91949, r=compiler-errors
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Add regression test for #91949

Closes #91949
This needs `build-fail` because the original bug only appeared with `cargo build`.
r? `@compiler-errors`
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Dylan-DPC committed May 23, 2022
2 parents b73f1c7 + ea9d2fb commit 6d366f1
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30 changes: 30 additions & 0 deletions src/test/ui/traits/issue-91949-hangs-on-recursion.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,30 @@
// build-fail
// error-pattern: overflow evaluating the requirement `(): Sized`
// error-pattern: function cannot return without recursing

// Regression test for #91949.
// This hanged *forever* on 1.56, fixed by #90423.

#![recursion_limit = "256"]

struct Wrapped<T>(T);

struct IteratorOfWrapped<T, I: Iterator<Item = T>>(I);

impl<T, I: Iterator<Item = T>> Iterator for IteratorOfWrapped<T, I> {
type Item = Wrapped<T>;
fn next(&mut self) -> Option<Wrapped<T>> {
self.0.next().map(Wrapped)
}
}

fn recurse<T>(elements: T) -> Vec<char>
where
T: Iterator<Item = ()>,
{
recurse(IteratorOfWrapped(elements).map(|t| t.0))
}

fn main() {
recurse(std::iter::empty());
}
25 changes: 25 additions & 0 deletions src/test/ui/traits/issue-91949-hangs-on-recursion.stderr
Original file line number Diff line number Diff line change
@@ -0,0 +1,25 @@
warning: function cannot return without recursing
--> $DIR/issue-91949-hangs-on-recursion.rs:21:1
|
LL | / fn recurse<T>(elements: T) -> Vec<char>
LL | | where
LL | | T: Iterator<Item = ()>,
LL | | {
LL | | recurse(IteratorOfWrapped(elements).map(|t| t.0))
| | ------------------------------------------------- recursive call site
LL | | }
| |_^ cannot return without recursing
|
= note: `#[warn(unconditional_recursion)]` on by default
= help: a `loop` may express intention better if this is on purpose

error[E0275]: overflow evaluating the requirement `(): Sized`
|
= help: consider increasing the recursion limit by adding a `#![recursion_limit = "512"]` attribute to your crate (`issue_91949_hangs_on_recursion`)
= note: required because of the requirements on the impl of `Iterator` for `std::iter::Empty<()>`
= note: 171 redundant requirements hidden
= note: required because of the requirements on the impl of `Iterator` for `IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), std::iter::Empty<()>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>, [closure@$DIR/issue-91949-hangs-on-recursion.rs:25:45: 25:52]>>`

error: aborting due to previous error; 1 warning emitted

For more information about this error, try `rustc --explain E0275`.

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